1. Field of the Invention
The present invention relates to sunroof mechanisms for vehicles and, more particularly, to a structural rail for such sunroof mechanisms.
2. Description of Related Art
Existing sunroof mechanisms for vehicles, such as cars, trucks, vans and sport-utility vehicles, typically include a sunroof panel that is movable with respect to an opening in a roof of the vehicle. Generally, the sunroof panel is mounted on a pair of track members that extend along an edge of the roof opening. A structural rail may be provided in cooperating relation with the track members to provide attachment points for the tracks and to mount a motor for moving the sunroof panel. Such sunroof mechanisms also may include a drive mechanism, such as a motor that drives a plurality of drive cables, to move a sunroof panel into the different operative positions thereof. In some known sunroof mechanisms, the drive cables are received within elongated metal tubes welded or bolted to the structural rail. The metal tubes act as an outer sheath, similarly to the outer sheath of a Bowden wire, and provides a pathway for the drive cables. Specifically, the internal diameters of the metal tubes are essentially the same as the outer diameters of the drive cables so that the cables, when driven, only move linearly within the metal tubes.
The drive cables may be subject to thermal expansion during increased temperatures. Because the internal diameters of the tubes are matched closely with the outer diameters of the cables, the cables cannot flex within the tubes to accommodate for this thermal expansion. Thus, the cables expand in the only direction permittedxe2x80x94the axial linear direction within the tubes. This is problematic because such expansion can interfere with operation of the sunroof mechanism, particularly in those where sensors measure sunroof travel based on factors directly or indirectly effected by the cable travel.
In another type of sunroof shown in German Patent DE 4422646, a plurality of tabs are punched from the structural rail to define a pair of pathways for receiving the cable. Specifically, the internal surfaces of the tabs define pathways for the cables. The cables are unsheathed and inserted in these pathways so that the tabs themselves act like the sheath in a Bowden wire. Thus, the tabs must be precisely punched so that the diameters of the pathways are essentially the same as the diameters of the cable. As a result, this arrangement not only suffers from the same problems noted above with respect to the use of metal tubes, it is also expensive to manufacture due to the low tolerances that must be maintained in the punching operation.
The present invention provides a sunroof mechanism for a vehicle having a roof and an opening therein. The sunroof mechanism comprises a pair of track members that is constructed to be mounted to the roof at side edge portions of the opening. Each of the track members has an elongated drive member receiving channel with a longitudinally extending opening. A sunroof panel assembly of a size to close the opening is movably received on the track assembly. The sunroof panel assembly is moveable with respect to the opening in the roof between an open position, wherein the panel member uncovers the opening and a closed position, wherein the panel member substantially closes the opening in the roof.
A rail assembly is coupled to the pair of track members at end portions thereof and extends therebetween. A pair of elongated flexible drive members are each coupled to the rail assembly and each extend to the drive member receiving channels. Each of the drive members have an end portion thereof connected to portions of the sunroof panel assembly extending through the longitudinally extending openings of the channels. A pair of tubular flexible guide sheaths has internal diameters that essentially correspond to external diameters of the drive members. The drive members are received within the sheaths such that the sheaths guide the drive members for axial movement therein. The drive member receiving channels also have internal diameters essentially that correspond to the external diameters of the drive members. The drive members are received within the channels such that the channels guide the drive members for axial movement therein.
A driving unit is coupled to the rail assembly and is operatively connected to each of the pair of flexible drive members such that operation of the driving unit drives the flexible drive members axially within the guide sheaths and the drive member receiving channels to move the sunroof panel in an opening direction towards the open position and in a closing direction towards the closed position.
The rail assembly comprises a plurality of mounting portions that define sheath receiving pathways. The guide sheaths are received within the sheath receiving pathways so as to mount the sheaths and the driving members therein to the rail assembly. The track members each also include a guide sheath receiving portion each open at one end to the drive member receiving channels and at an opposite end to the rail assembly. The guide sheath receiving portions are oversized relative to the channels. The guide sheaths have end portions thereof received in the guide sheath receiving portions in axially spaced relation from the drive member receiving channels. The axially spaced relation enables the guide sheaths to elongate axially due to thermal expansion.
Other objects, features, and advantages will become apparent from the following detailed description, the accompanying drawings, and the appended claims.